Method for determining amount of regenerative braking

Abstract

A method for determining an amount of regenerative braking includes: determining a possible amount of regenerative braking at a time of braking a vehicle; distributing a first amount of regenerative braking up to the possible amount of regenerative braking as the amount of regenerative braking; distributing a second amount of regenerative braking remaining from the possible amount of regenerative braking as an amount of hydraulic braking; and performing, first, regenerative braking by issuing a motor torque instruction according to the possible amount of regenerative braking and, second, friction braking using the amount of hydraulic braking.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims under 35 U.S.C. §119(a) priority to and the benefit of Korean Patent Application No. 10-2014-0156847 filed on Nov. 12, 2014, the entire contents of which are incorporated herein by reference.BACKGROUND[0002](a) Technical Field[0003]The present disclosure relates generally to a method for determining an amount of regenerative braking. More particularly, it relates to a method for determining an amount of regenerative braking to maximize the amount of regenerative braking by making an early stage control of the regenerative braking be performed at an early stage of braking.[0004](b) Background Art[0005]The travelling modes of hybrid vehicles include an Electric Vehicle (EV) mode which is a pure electric vehicle mode using only a motor power, a Hybrid Electric Vehicle (HEV) mode which utilizes an engine as the primary power source and a motor as auxiliary power, and a Regenerative Braking (RB) mode which charges a batt...

AI Technical Summary

Benefits of technology

The disclosed embodiments are designed to solve problems in hydraulic braking systems by prioritizing regenerative braking and maximizing its amount. By controlling when regenerative braking starts, the system can ensure stable braking and maximize the amount of braking provided. This is accomplished by integrating regenerative braking with conventional hydraulic braking, making it possible to achieve efficient and reliable braking control.

Problems solved by technology

Furthermore a case may occur where the regenerative braking is limited due to reasons of motor temperature, a battery charge condition, a speed change procedure of a transmission, and the like.

Meanwhile, at the time of braking, in case of performing the hydraulic braking after first checking whether the regenerative braking is actuated without performing the hydraulic braking, since a brake delay time of at least 20 ms can be generated, there may be a risk of accidents.

First, there is a problem of fuel ratio aggravation. The regenerative braking is a technology of converting energy into electric energy at the time of braking and is directly related to the fuel ratio, so that an increase in the amount of regenerative braking at once equates to fuel ratio improvement. However, since the hydraulic braking is first performed to secure the braking safety, i.e., since the hydraulic pressure is unconditionally first used at the time of early stage braking, fuel ratio aggravation due to the loss of the amount of regenerative braking is caused.

Second, there is a problem of aggravation of drive. At the early stage of braking, a control is performed in such a way that an oil pressure of at least 1 bar is applied. Thereafter, a total amount of braking of the regenerative braking and the hydraulic braking is made according to the amount of braking that a driver requires by reducing the oil pressure at the time of performing the regenerative braking. However, since the response of the regenerative braking is slow, there may occur a feeling of suddenness and discomfort at the initial stage of braking, and in the case of downward adjusting the increase gradient of the amount of regenerative braking to minimize the discomfort, eventually, a vicious circle of reducing the amount of regenerative braking and aggravating the fuel ratio is repeated.

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